The standard enthalpy of formation of NH₃ is– 46.0 kJmol^–1. If the enthalpy of formation of H₂ from its atoms is – 436 kJ mol^–1 and that of N₂ is – 712 kJ mol^–1,the average bond enthalpy of N – H bond is NH₃ is

• -964 kJ mol^-1

• +352 kJ mol^-1

• +1056 kJ mol^-1

• +1056 kJ mol^-1

The energy required to break one mole of Cl— Cl bonds in Cl2 is 242 kJ mol^–. The longest wavelength of light capable of breaking a single Cl — Cl bond is
(c= 3 x 10⁸ ms^–1and N_A = 6.02 x 10²³ mol^–1)

• 594 nm

• 640 nm

• 700 nm

• 700 nm

The solubility product of silver bromide is 5.0 x 10^-13. The quantity of potassium bromide (molar mass taken as 120 g mol^–1)to be added to 1 litre of 0.05 M solution of silver nitrate to start the precipitation of AgBr is

• 1.2 x 10^-10 g 

• 1.2 x 10^-9 g

• 6.2 x 10^-5 g 

• 6.2 x 10^-5 g 

For a particular reversible reaction at temperature T, ΔH and ΔS were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when 

• T_e>T

• T >T_e

• T_e is 5 times T

• T_e is 5 times T

Δ U is equal to

• Isochoric work

• Isobaric work

• Adiabatic work

• Adiabatic work

Given
C(grahite) + O₂(g) → CO₂(g)
Δ_rH°  = - 393.5 kJ mol^-1
H₂(g) + 1/2O₂(g) → H₂O (l)
Δ_rH°  = +890.3 kJ mol^-1
Based on the above thermochemical equations, the value of Δ_rH° at 298 K for the reaction
C(grahite) + 2H₂(g) →CH₄ will be

•  +74.8 kJ mol^–1 

• +144.0 kJ mol^–1

• –74.8 kJ mol^–1

• –74.8 kJ mol^–1

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is
CH₃OH(l) + 3/2O₂(g) → CO₂(g) + 2H₂O(l)
At 298 K standard Gibb’s energies of formation for CH₃OH(l), H₂O(l) and CO₂(g) are –166.2, –237.2 and –394.4 kJ mol^–1 respectively. If
standard enthalpy of combustion of methanol is –726 kJ mol^–1, efficiency of the fuel cell will be:

• 80%

• 97%

• 87%

• 87%

Which one of the following reactions of Xenon compounds is not feasible?

• XeO₃+ 6HF → XeF₆  + 3H₂O

• 3XeF₄ +6H₂O → Xe+XeO₃+ 12HF+ 1.5O₂

• 2XeF₂ + 2H₂O → 2Xe + 4HF +O₂

• 2XeF₂ + 2H₂O → 2Xe + 4HF +O₂

Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below


The energy involved in conversion of 

• 152 kJ mol^-

• -610 kJ mol^-

• -850  kJ mol^-

• -850  kJ mol^-

Standard entropy of X₂, Y₂ and XY₃ are 60, 40 and 50 JK⁻¹
mol −1, respectively. For the reaction,1/2X₂ + 3/2Y₂, ΔH = -30 kJ,to be at equilibrium, the temperature will be

• 1250 K

• 500 K 

• 750 K

• 750 K